Heterozygosity for two novel null alleles of the<i>KEL</i>gene causes the Kell‐null phenotype in a Japanese woman

Abstract

The Kell-null (Ko) phenotype is rare and it does not express the Kell antigens on erythrocyte membranes. Recently, several distinct missense and nonsense base substitutions in the coding region and the donor splice site of intron 3 were identified in the KEL gene in individuals with the Ko phenotype. We analysed both genomic DNA and cDNA sequences of the KEL gene in a Japanese woman with the Ko phenotype. She was found to be heterozygous for two novel null KEL alleles. One allele contained an A to G substitution in intron 5 that changes the 3'-splice site of intron 5 from AAG to AGG, resulting in a reading frameshift by a single guanine insertion in KEL mRNA, and the other allele contained a single G to A substitution in exon 12 (codon 459) creating a termination codon. Neither mutation was found in 114 randomly selected Japanese individuals. The results suggested that the Ko blood group phenotype might be owing to several distinct non-functional alleles without any prevalent allele.